class X {
  function int(int: Int(isPositive)): Int(isPositive) = int
  function l(l: List<String(!isEmpty)>): List<String(!isEmpty)> = l
  function map(map: Map<String(!isEmpty), Int(isPositive)>(!isEmpty)): Map<String(!isEmpty), Int(isPositive)>(!isEmpty) = map
  function nullable(nullable: String(!isEmpty)?): String(!isEmpty)? = nullable
}

local x = new X {}

res0 = x.int(3)
res1 = x.l(List("1", "2"))
res2 = x.map(Map("1", 1, "2", 2))
res3 = x.nullable("1")
res4 = x.nullable(null)
